The present invention relates to the preparation of collagen-coated foodstuffs, especially sausages.
There are two approaches to making sausages. The first is to take natural or artificial sausage casing and stuff it with sausage meat. In recent times, it has become known to coextrude a strand of sausage material which has an inner core of meat emulsion having an outer surface material that can be coagulated to provide an encasement for the strand. The outer surface material may consist of a gel with a collagen protein. The coagulation normally includes subjecting the extruded strand to a brine (salt) solution. The brine is applied immediately after the strand is extruded to coagulate the proteins in the gel.
In the generally known methods, the water content of the gel coating is lowered with the assistance of osmosis by leading the strand of food stuffs through a concentrated salt bath. Thereafter, an air drying step is used to further enhance the strength of the sausage casing. After this treatment, the mechanical properties of the casing are insufficient to allow for conventional twist linking, clipping, or hanging of the foodstuff, i.e. sausage strand. With this usual method, it is habitual to crimp the coextruded strand of foodstuff and cut it into individual elements. These elements are thereafter placed in a hot air dryer for the treatment of individual elements, for example, drying, smoking, etc. This known method has a number of disadvantages. First, sausages manufactured with this coextrusion method tend to have inferior qualities, including inferior color, taste, or appearance in comparison to sausages which have been manufactured with a natural or artificial casing. This is due to long dwelling times of the meat in the brine solution which are necessary for sufficient coagulation of the collagen gel. During this time, the brine solution is absorbed into the meat which can cause an off-taste.
Another disadvantage with the coextrusion process is that standard smoking and/or cooking installations cannot be used economically in the further processing of the meat. The low casing strength, resulting the treatment with brine, requires the use of a smoking and cooking installation where the crimp/cut sausages are transported on a horizontal belt. In standard smoking and cooking installations the sausages strands are hung in loops on sticks and thus processed. Apart from the coextrusion process requiring an investment in new smoking and cooking installations, the processing of sausage flat on a belt gives a different and unwanted appearance from the conventional natural or artificial casesd sausages.
International patent application WO930/12660 to Morgan et al. discloses a coextrusion method intended to solve the aforementioned problems. This method also includes the steps of coextruding a mainly equal layer of collagen gel around an extruded edible product and the subsequent chemical coagulation of the extruded collagen gel while using a chemical coagulation means, though without the step of drying with hot air in order to achieve a coagulated collagen casing around the edible product. Principally this is achieved by prolonging the brine treatment with a more effective brine solution compared to the traditional coextrusion process. In the latter process sodium chloride brine solutions are commonly used. In Morgan et al. the more effective brine solution comprises using other salts which give a higher osmotic drying while reducing the taste and appearance effects which limit the traditional methods. Proposed is the use of Sodium Carbonate. The dissolvability of sodium carbonate and thus osmotic drying strength of the brine is raisec by heating the brine solution. However, this disclosed method also does not adequately resolve the aforementioned problems and disadvantages.
First, the sausages manufactured using the method disclosed by Morgan et al. still do not have sufficient casing strength to allow traditional processing i.e. hanging on sticks. For instance, when strands of edible foodstuffs which are thus manufactured are hung, the partly fluid meat mix flows downward, giving the edible foodstuff an undesirable cone shape. An additional disadvantage is that, due to the lengthy stay in the coagulation bath, the salt content in the casing and in the meat mix, is high. In spite of the type of salts used in the brine this results in unwanted organoleptical and physical changes of the sausage mix, such as in taste, consistency and firmness of the meat mix. Further, the high solvent temperatures necessary to complete the coagulation process tend to discolor the meat, and weaken the casing by protein denaturation.
It is therefore a principal object of the present invention to provide a method for manufacturing coextruded food strands with an edible casing in which the previous problems and disadvantages of the known coextrusion methods do not occur.
It is a further object of the present invention to provide a novel means of coagulating collagen containing gel on a coextruded food product.
It is still a further object of the present invention to provide a method for coagulating collagen containing gel in the coextrusion process which allows for shorter coagulation times.
It is yet a further object of the present invention to provide a means of coagulating collagen containing gel in the coextrusion process which does not negatively influence the organoleptic properties of the foodstuff.
It is yet a further object of the present invention to provide a means of coagulating collagen containing gel in the coextrusion process which eliminates the need for air drying following coagulation.
It is still a further object to the present invention to provide a means of coagulating collagen gel in the coextrusion process which is economical to use.
An additional object of the present invention is to create by co-extrusion a substantially uniform layer of a collagen-containing gel, with a dry matter of between 3 and 25%, around an elongated strand of foodstuff wherein the gel is acidified using an inorganic acid which is set in contact with an aqueous solution containing a highly dissolvable salt.
These and other objects will become clear from the following description of the invention.